The effect of irradiation on the stability of precipitates in Zr-2.5 WT% Nb alloys

Precipitate Stability in a Zr–2.5Nb–0.5Cu Alloy under Heavy Ion Irradiation

“…In the Zircaloys, the radiation-induced the dissolution of Zr(Cr,Fe) 2 and Zr 2 (Ni,Fe) secondary precipitation in the matrix and at grain boundaries, and the depletion of Cr and Fe from the precipitates have been reported by many authors [1][2][3][4][5][6]. In Zr-Nb alloys, the dissolution of Nb and the redistribution of Fe are also clearly observed under higher dose irradiation (>3 dpa) [3,7]. These changes will affect the material performance in the reactors such as corrosion behavior and irradiation growth.…”

“…The defects produced by irradiation are expected to enhance the solute diffusion rate due to the increase of solute solubility and a faster diffusion channel. Nuttall et al [7] found an enhancement of solute diffusion rates in Zr-2.5Nb by irradiation, which exceeds the thermal diffusion rate by several orders of magnitude. Similar observations were reported by Motta et al [45] in the same alloy.…”

“…To our knowledge, this is the first time the direct dependence of precipitate stability on the surrounding matrix microstructure has been reported. The zirconium alloys used in early studies such as Zircaloy-2 [1][2][3]26], Zircaloy-4 [1,26,27], Zr-2.5Nb [5,7,24,33], and HANA (high performance alloy for nuclear applications) [34] are all in the recrystallized state and do not exhibit martensitic structures. The main differences between type i and type iii structures are the amount of boundaries.…”

“…In the past few decades, some research works have reported the effect of irradiation on precipitate and microstructure stability in Zr-2.5Nb [3,7]. A temperature and irradiation fluence dependent precipitate stability and the distribution of alloying elements was reported.…”

“…A temperature and irradiation fluence dependent precipitate stability and the distribution of alloying elements was reported. High temperatures and high doses will enhance the dissolution of β-Zr and the depletion of Fe from the particles to the matrix [3,5,7,19]. However, the microstructure and precipitates of the as-processed Zr-2.5Nb pressure tube alloy have many differences to the proposed Zr spacer material.…”